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Dock Homology Region 2, a GEF domain, of Class A Dedicator of Cytokinesis 5 Dock5 is an atypical guanine nucleotide exchange factor (GEF) that lacks the conventional Dbl homology (DH) domain. As a GEF, it activates small GTPases by exchanging bound GDP for free GTP. It functions upstream of Rac1 to regulate osteoclast function. DOCK proteins are divided into four classes (A-D) based on sequence similarity and domain architecture; class A includes Dock1, 2 and 5. All DOCKs contain two homology domains: the DHR-1 (Dock homology region-1), also called CZH1 (CED-5, Dock180, and MBC-zizimin homology 1), and DHR-2 (also called CZH2 or Docker). The DHR-1 domain binds phosphatidylinositol-3,4,5-triphosphate. This alignment model represents the DHR-2 domain of Dock5, which contains the catalytic GEF activity for Rac and/or Cdc42. Class A DOCKs, like Dock5, are specific GEFs for Rac and they contain an SH3 domain at the N-terminal region and a PxxP motif at the C-terminus. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",